Not entirely accurate, but a pretty good try by ChatGPT
If you are like me, you throw around the terms brass and bronze pretty casually and without any exactness.
Musical instruments are brass, plumbing is brass, old doorknobs are brass. Meanwhile sculptures are bronze, medals, things you might find on a ship, old swords and armor from the age that bears the same name. And so on. I also see coins made from both alloys.
I mean I have a list of things in my head for each alloy, but if you asked me I wouldn't have been able to tell you the difference.
So.... what is the difference?
The other day when I wrote my shell case penny post I looked up the info for the coin in Wikipedia, just to make sure I got the details correct. Turns out the 95% copper, 5% zinc alloy that made up those pennies is brass. Not only that, but it is a specific type of brass called gilding metal.
Just for the sake of completion:
Pennies from...
- ...before 1856 were 100% copper
- ...1856 to 1864 were NS-12 (a type of cupronickel)
- ...1864 to 1942 were bronze
- ...1943 were zinc-coated steel
- ...1944 to 1946 were gilding metal (a type of brass)
- ...1947 to 1962 were bronze
- ...1962 to Sept 1982 were gilding metal (a type of brass)
- ...Oct 1982 to 2025 were copper-plated zinc
So what exactly are these alloys? Starting with the two big categories:
Bronze is traditionally an alloy of copper and tin, but might contain other elements such as aluminum, phosphorus, or silicon. Brass meanwhile is an alloy of copper and zinc. The basic difference is that brass is more malleable and more yellowish, while bronze is more brittle and has a reddish-brown color.
Then we come to gilding metal, a specific type of brass that is exactly 95% copper and 5% zinc. It was named for its use in gilding (coating things with gold). Due to the high copper content, it is softer and more malleable than typical brass.
Incidentally, that alloy the penny used from 1856 to 1864 called NS-12 is an interesting one. Just like gilding metal is a specific kind of brass, NS-12 is a specific kind of cupronickel. It is 88% copper and 12% nickel. The penny moved to it because the nickel lobby petitioned strongly for US coins to switch to the metal. The US decided it would be a good way to reduce reliance on precious metals. NS-12 is fairly pale with a silvery hue. While this color was different from the previous 100% copper pennies, it was still different enough to stand out from other coins. In addition to being cheaper to make, NS-12 is less prone to tarnishing. Unlike bronze or brass, which can develop a greenish patina over time, NS-12’s higher nickel content slows down oxidation, keeping its silvery appearance for longer.
But then the American Civil War broke out and the price of nickel went up a lot, making NS-12 suddenly not so attractive and motivating the switch to bronze.
Anyway, so there you go. Next time you look at a reddish-brown/yellow coin and someone throws out the name bronze or brass, you will have a better idea of exactly what metals that is!
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David is an American teacher and translator lost in Japan, trying to capture the beauty of this country one photo at a time and searching for the perfect haiku. He blogs here and at laspina.org. Write him on Mastodon. |
